mikanb

I have upgraded existing code with previous modifications to expand measurement range up to 50 Ohms and to make this ESR meter autoranging in the range of 0-50 Ohms which should be more than enough range for the ESR measurement. The code is included in the attachment and on the schematic you have to add one more PNP transistor with the same configuration as Q1 but with the 1k resistor instead of 100R (1k is for upper range measurement). Pinout in my sketch version is different in order to match my board so you will have to modify it according to your board settings.Any comments/suggestions are welcome...

Baravantan

Hello everyone, and thank you for sharing your work.I built the ESR meter using an Arduino UNO and a lcd display CDL4162-HD44780.My version can work in two ways: with Arduino UNO connected to the board face down, and in standalone mode.In the first case, only the bottom side of the pcb is required (single side)I also added a function that allows me, by selecting the right value of the DUT, to know immediately if it is good or not.BUT there is a problem: If I measure a 1ohm resistor, the reading is quite correct, but if I measure 150mohm or 75mOhm, the reading is totally wrong. Is there anyone who can help me? Thank you. :~

Hi Baravantan,To answer your last question, yes, I have measured what seem to be good values in the milliOhm range. I have a 100mOhm precision resistor and have measured many capacitors with what appears to be reasonable and repeatable results.I took a quick look at your code and all appears to be OK with the actual calcESR routine. I didn't look at your PCB layout so I can't say more than that in my proto-board build I used the schematic exactly as in the original post EXCEPT that I used a 10microFarad cap and a 110Ohm resistor in the pulse circuit (47micro and 100 Ohm in the original).I did notice in testing that the whole thing is very sensitive to the declared supply voltage and the value of this resistor. And I noticed in your code the following...

double Vin_LO = 4700; // milliVoltsuint16_t Rs_LO = 110; // Ohms

Are you actually using a 110 Ohm resistor? And is your supply voltage really only 4,7 V? Unless these (and the Vref voltage) are well defined, the calculation can be very non-linear.Anyway, hope this helps.

cepc

Sorry, I am just a breadboard/point-to-point/proto-board type. My main need for an ESR meter is to troubleshoot old audio gear and test equipment.

Hello Totoro , I am having a hard time wrapping my head around which pins you hooked up to the 7 segment displays, can you possibly draw something quick showing pinouts? i dont want to use a lcd display, im going to make a smd version of the board and will post the results after i have a working prototype.